1. Field
Embodiments of the present invention relate to a pedal simulator for an active brake system which may improve pedal feel.
2. Description of the Related Art
Generally, an active hydraulic boost (AHB) is a brake system that generates braking force when a driver pushes the pedal by sensing the push through an electronic control unit and supplying hydraulic pressure to the master cylinder through operation of a hydraulic pressure generation unit, thereby transferring hydraulic pressure for braking to a wheel cylinder of each wheel. In the case of such AHB, when the driver pushes the pedal during normal braking, a pedal displacement sensor senses the displacement of the brake pedal. The electronic control unit operates the hydraulic pressure generation unit and controls supply of the hydraulic oil stored in a hydraulic oil reservoir to a boost chamber of the master cylinder to produce pressure in the master cylinder. The pressure produced in the master cylinder presses a piston in the master cylinder to produce hydraulic brake pressure. This hydraulic brake pressure is transferred to the wheel cylinder to produce braking force.
In the case that the pressure in the master cylinder changes during regenerative braking, the resulting force may be directly transferred to the brake pedal, thereby adversely affecting pedal feel. When the pedal feel is degraded in this way, a large difference occurs between pedal feel that the driver receives in braking and the actual level of pressure applied to the brake disc of the brake pad in the wheel cylinder, resulting in excessive or insufficient braking. Thereby, disposable components such as the brake pad may need to be frequently replaced and sudden braking or failure of braking leading to a traffic accident may occur.
In conventional cases, a pedal simulator is adopted for the AHB to provide reaction force to the brake pedal. Such a pedal simulator uses, as disclosed in Korean Patent No. 10-0657576, two springs provided therein as shock absorbing members to absorb shock to a simulator piston. However, the two springs merely produces pedal feel of the brake linearly varying along the straight lines as shown in FIG. 1, and may not provide required pedal feel.